In recent years, in imaging systems such as video cameras, an anti-shake function that prevents vibrations such as camera shake has become indispensable, and various types of anti-shake optical systems have been proposed.
For example, in the video camera disclosed in JP H8-29737A, an optical system for correcting camera shake made of two lenses is placed before a zoom lens, and image fluctuations due to camera shake are corrected by shifting one of those lenses perpendicularly with respect to the optical axis.
In the video camera disclosed in JP H7-128619A, a zoom lens of four lens groups is used, and image fluctuations due to camera shake are corrected by shifting some of the lenses of the third lens group, which is made of a plurality of lenses, perpendicularly with respect to the optical axis.
However, in the video camera disclosed in JP H8-29737A, since the optical system for correcting camera shake is placed before the zoom lens, the lens diameter of the optical system for correcting camera shake becomes large. As a consequence the video camera itself also becomes larger, and the load on the driving system becomes larger, which is disadvantageous with regard to making the video camera smaller and lighter, and reducing its power consumption.
Furthermore, in the video camera disclosed in JP H7-128619A, image fluctuations due to camera shake are corrected by shifting perpendicularly with respect to the optical axis some of the lenses of the third lens group, which is fixed with respect to the image plane, so that it is advantageous with regard to size compared to video cameras in which the optical system for correcting camera shake is placed before the zoom lens, but since the lens group for correcting camera shake is made of three lenses, the load on the actuator is large, and the zoom ratio is small, only about 1:10.